[Access] Implement integration test for new websockets

[UlyanaAndrukhiv]

Closes: #6641, #6876

Note: This PR related with #6737

Context

This pull request adds integration tests to verify the functionality of the new WebSockets implementation and incorporates the following updates:

1. Fixes from integration test results.
   Errors identified during integration testing have been resolved, ensuring stable and expected behavior for all supported scenarios.

2. Max subscriptions per connection functionality.
   The functionality has been implemented, enforcing a limit on the number of active subscriptions allowed per Websocket connection.

3. Integration test scenarios:

• Happy paths:

  • Subscribing to any topic, ensuring a successful subscription response and expected results.
  • Unsubscribing from a topic successfully.

• Error cases:

  • Attempting to subscribe with invalid data.
  • Attempting to unsubscribe with invalid data.

• Additional behaviors:

  • Retrieving a list of all active subscriptions.
  • Verifying client inactivity tracking and connection loss handling.
  • Verifying the Websockets MaxSubscriptionsPerConnection limits functionality

[illia-malachyn]

We need to get this over with. The more time we don't review it, the more time we'll spend to recall what has been done in this PR. I have a capacity rn, so I'll review it on Monday if nothing special comes up.